StretchingStudies have been done in regards to flexibility and its relationship with running economy and with injury prevention. We will discuss both here. At the end of each section you will find some articles linking to more in-depth information. Links have been provided to those with public access. Relationship to Running EconomyIt still has not been decided whether flexibility is good for runners nor how much flexibility is too much. Generally, studies focus on muscles in the thighs and calves as those are the most used in running. Some have shown that less flexibility in running is directly related to more economical running while others have shown no correlation. The argument for those supporting less flexibility is that less flexibility leads to less erratic movements while running. Those that argue against, however, have seen no conclusive evidence. See the following articles:
Relationship to Soreness and InjuryResearch has shown that the risks associated with static stretching overpower the benefits. There is a consensus that static stretching, whether done before or after exercising, does not strengthen muscles, thus it has no role in preventing injury. Fitness and age have been found to be the biggest factors in determining injury risk. Some reasons stretching may actually induce injury are:
Though many claim to find a reduction in soreness as a result of stretching, that reduction has been found to be very limited. On a scale of 1-100 for soreness, it effectiveness is less than 1. Balancing that small benefit in soreness with the possibility of negative effects with injury makes stretching look much less favorable. See the following articles:
TerrainThe best surface for runners to run on is that of a track. Research has been done relating the terrain a runner trains on to wearing down of the joints. Most research focuses on the impact and amplitude of the shock waves seen as the runner's foot strikes the ground, most importantly at the heel. Perhaps surprisingly, running on grass creates greater shock waves in the bones than either a track surface or asphalt. The other two have relatively similar impact profiles. Scientists hypothesize that it is the uncertainty a runner has while running on grass that causes greater impact. However, when the surfaces themselves are analyzed, it has been shown that the peak deceleration in asphalt is much greater over a much shorter period of time as compared to a track surface. The surface of a track is therefore the most preferred for preventing injury because it both reduces shock waves and is even, as opposed to a road that is much less flexible and may be uneven. Studies have also concluded that running on uneven surfaces, such as on trails or anywhere 'off-road' requires more energy input from the runner to make up for the lack of consistency in the terrain. Doing so creates a more erratic stride and puts stresses where the runner may not have the ability to support them. However, if you are racing 'off-road', it would be beneficial to train on an uneven surface to build up the necessary muscular support. This will allow you to run at an accelerated pace in the race with a lower risk for injury. See the following articles:
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